Secrecy, smoke and arcane rituals mark the conclave, the secretive process by which a new pope will be elected after the death of Pope Francis on Easter Monday.

The Vatican has announced that the conclave will start on May 7. Nobody knows how long it will last. Roman Catholic cardinals from around the world will be led into the Sistine Chapel, then the doors will be closed.

The cardinals have to take an oath of secrecy – the punishment for divulging to the outside world anything that happens inside the chapel is instant excommunication.

For the last conclave in 2013, which followed the historic resignation of Pope Benedict XVI, an oath of secrecy was also taken by members of the Swiss Guard and Vatican gendarmerie, the city state’s police force, as well as the doctors and nurses who assisted elderly or infirm cardinals.

The chapel will have been swept for bugs and other recording devices, and cardinals will be banned from using laptops or mobile phones. A Vatican master of ceremonies will pronounce the words “Extra omnes” (Everyone out), ordering staff and aides to leave the chapel so that only the cardinal electors remain.

The word conclave comes from “cum clave”, Latin for “with a key”, a reference to the fact that the red-robed “princes of the Church” were traditionally locked inside the chapel.

It is not a bad place in which to be sequestered: the walls are adorned with frescoes by Renaissance artists, including Michelangelo, Perugino and Botticelli. The chapel was built in the late 15th century for Pope Sixtus IV – hence its name.